In recent years, a light emitting device using a luminescent material made of quantum dots has been proposed in, for example, Patent Literature 1 below. Specifically, Patent Literature 1 proposes a light emitting device (light sheet) in which a film or layer containing quantum dots is disposed on at least a portion of a surface of a waveguide. The light emitting device described in this Patent Literature 1 is a device for emitting, upon irradiation with excitation light, light having a different wavelength from the excitation light.